So far, Sen. Kerry has far outpaced his competitors, raking in more than $150,000 since January. Bush, whose campaign launched its own Amazon fund-raising page 10 days later, in February, comes in a distant second place with $30,000 and change.

The Bush campaign may take solace in the fact that it has raised nearly $100 million more than the Kerry campaign overall. According to opensecrets.org, Bush had raised $185 million as of April 20, while Kerry had raised $86 million.

Since the meteoric, if brief, success of Democratic candidate Howard Dean's campaign fund-raising online, campaigns have sought to match it with their own Internet efforts. The Kerry campaign said late last month that it had raised more than $34 million through its Web site.

Amazon could not immediately be reached for comment on the fund-raising site.

But in responses to frequently asked questions, Amazon said the purpose of the site was to make it easier for people to donate to qualifying candidates.

"We're trying to take the friction out of grassroots contributions to presidential candidates," the site reads. "We're making it as easy for people to contribute as it is to buy the latest 'Harry Potter.'"

Amazon explained that election law forbade the company from donating services to the political campaigns, so it was charging its normal payment fee of 25 cents per contribution and 2.5 percent of the contribution amount. Proceeds will eventually go to a nonprofit educational group called Kids Voting USA.

In addition to the Republican incumbent and the presumptive Democratic nominee, a handful of other candidates are raising funds through Amazon. A comparatively strong contender for third place is Libertarian candidate Gary Nolan, whose campaign has raised nearly $18,000 on the site. Democratic candidates Dennis Kucinich, Al Sharpton, and Lyndon Larouche rounded out the Amazon.com roster along with other Libertarians and third-party candidates.

The site is restricted to candidates who have met a threshold of fund-raising and spending. Notably missing from the fray is controversial independent candidate Ralph Nader, who chose not to participate, Amazon said.